Floor insulation - article

[jacko555]

Planning to insulate suspended ground floor, inspired from threads here.
Basically add some netting, whack in loft insulation, dont encapsulate cables, job done, time for a beer.

Read this article https://www.eco-home-essentials.co.uk/underfloor-insulation.html

Says loft insulation (non hygroscopic) is bad. Needs a vcl and breathable membrane. Etc.

Obviously this complicates things and increases the cost significantly.

Thoughts? Is the article full of sh1t and an ideal?

I don't see how the proposed method (insulation and netting) can be a bad thing. I'm having around 50sqm of parquet, on top of ply, on top of the floorboards. It's a massive area and anything to prevent drafts rounds the skirts and pride some degree of insulation is good.

 

[Mr Chibs]

I used that orange barrier mesh and made cradles for mine, I just used rock wool, full depth of joists 175mm.

I went to look at wood flooring and they recommended that you put building paper on top of the joists and insulation... its like brown paper with a layer of bitumen in the middle, this is what I used, haven't noticed any issues.

As far as I'm aware, rock wool is moisture resistant and not degrade, so I'm not sure it's really an issue.
If the ventilation is good under the floor, don't really think you've much to worry about.

 

[jacko555]

I was looking at glasswool (non hygroscopic). Rockwool is hygroscopic, as its cheaper.
Wonder what benefit the building paper provides?

 

[Mr Chibs]

Thinking back, I used loft roll, Knauf, this is non hygroscopic.

Building paper is to stop moisture that gets through any gaps. Dare say your VCL is the same type of idea.

 

[jacko555]

Just noodling around having a read. This place https://www.permagard.co.uk/advice/installing-vcl-vapour-control-layer says

Do I need Vapour Control Layers for my floor?
In ground floor applications such as concrete slabs and beam and block applications, a VCL is required on the warm side of the insulation. This will also help protect the insulation from wet screed or concrete.

Suspended timber floors are slightly different. There are differing opinions around whether to introduce a VCL or not, and where to place it. If the VCL is not installed properly, it can create more issues with condensation.

In an ideal scenario, the VCL would be placed to the top side of the joists before boards are laid. The insulation would be below this, meaning that the VCL is on the warm side of the insulation. This would then stop warm, moist air from entering the structural element

So to stop warm moist house air condensing. Makes sense.

Now thinking about my floor - ply and parquet glued and screwed. Only risk will be around the edges.

 

[jacko555]

Paging @JobAndKnock

What are your thoughts on the best way to prevent drafts on the perimeter of a suspended floor, that will be overboarded in ply and parquet laid on top? Skirts and architraves are being replaced so full access is avail.

There is a definite draft issue now.

I've seen you talk about compriband before. Suitable? Or just stuff as much loft insulation in the gaps before the ply?